PYL-W0612 deepsource replace unused vars

[HaleySchuhl]

Describe your changes
Resolving issue PYL-W0612 REPLACE UNUSED VARS

Type of update
Is this a:

• Bug fix
• New feature or feature enhancement
• Update to documentation
• Work in progress

Associated issues
#1382

Additional context
Add any other context about the problem here.

For the reviewer
See this page for instructions on how to review the pull request.

• PR functionality reviewed in a Jupyter Notebook
• All tests pass
• Test coverage remains 100%
• Documentation tested
• New documentation pages added to plantcv/mkdocs.yml
• Changes to function input/output signatures added to updating.md
• Code reviewed
• PR approved

[codecov]

Codecov Report

Merging #1395 (5518c43) into main (c0d7961) will not change coverage.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #1395   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          158       158           
  Lines         6940      6925   -15     
=========================================
- Hits          6940      6925   -15     

Flag	Coverage Δ
unittests	100.00% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
plantcv/learn/naive_bayes.py	100.00% <100.00%> (ø)
plantcv/parallel/__init__.py	100.00% <100.00%> (ø)
plantcv/parallel/job_builder.py	100.00% <100.00%> (ø)
plantcv/parallel/parsers.py	100.00% <100.00%> (ø)
plantcv/parallel/process_results.py	100.00% <100.00%> (ø)
plantcv/plantcv/_helpers.py	100.00% <100.00%> (ø)
plantcv/plantcv/analyze/bound_horizontal.py	100.00% <100.00%> (ø)
plantcv/plantcv/analyze/bound_vertical.py	100.00% <100.00%> (ø)
plantcv/plantcv/analyze/grayscale.py	100.00% <100.00%> (ø)
plantcv/plantcv/analyze/size.py	100.00% <100.00%> (ø)
... and 17 more

[HaleySchuhl]

Might have one more deepsource complaint